The paper discusses the advantages and disadvantages of 3D surface-shape information on cartridge cases as a means of matching a cartridge case to a particular firearm. The first main section of the paper describes how the 3D shape of firearm evidence is acquired. It presents an overview of the system's architecture and describes the acquisition subsystem, a prototype acquisition subsystem, sampling issues in acquisition, the analysis subsystem, and a prototype analysis subsystem. The paper's next section addresses visual analysis with 3D surface topography of firearm evidence. Topics covered are firearm identification through a comparison of visual shapes, 3D surface topography and shape visualization, and the 3D virtual comparison microscope. The last section of the paper discusses quantitative measurement to support firearm identification. It focuses on quantitative measurement for the purpose of comparison, simple types of measurement, measurement through roughness parameters, data preprocessing for measurement, cross-correlation as a similarity metric, and selective comparison issues. In introducing the concept of the 3D virtual comparison microscope, this paper is not proposing fully automated identification, but rather a new set of tools for visual enhancement and quantitative measurement of shape properties. This technology aids but does not replace the firearm examiner in making the final decision about whether firearm evidence came from a particular firearm. 18 figures and 17 references